Endless-track vehicle



July 3Q, 1923.

L. K. DAVIS ENDLES S TRACK VEHICLE Filed March 20 1925 2 Shams-Sheet 1July E0, 1923.

1 4611 6328 L. K. DAVIS ENDLESS TRACK VEHICLE Filed March 20, 1923 2Sheets-Sheet 2 mmwl Lewis 1712mm STTS Patented duly lid, l

DAVI5, 015 WASHINGTON, ElllQTEIECT OF GOJL'UMBLA,

ll LESS-TRACK VEHICLE.

Application filed March 20, 1928. Serial 1110. 626,378.

To all whom it may concern:

Be it known that l, Luwrs K. DAvIs, a citizen of the United States,residing in the city of Washington District of Columbia, have inventedcertain new and useful Improvements in Endless-Track Vehicles, or whichthe following is a specification.

This invention relates" to vehicles of the class in which endless tracksor tractor belts are employed to sustain the vehicle and traverse theground, and especially to'that class of such vehicles in which the trackislald down in front of bogies or other supporting devices which bear onthe lower runs of the belts.

Various methods of steering such vehicles havebeen suggested, but nonehave been entirely satisfactory owing to the fact that usually insteering, those portions of the track which bear on the ground are movedsidewise and skid or-scrape the ground and often considerable strain isthus placed on the mechanism. Such vehicles when provided with steeringwheels at the front and tractor belts at the rear may be steered 1n theusual way and it has heretofore been sugted to steer such vehicles bybending the belts laterally and also to brake one of the driving pulleysand by difierential gearing to increase the speed of the other drivingpulley. in such last mentioned cases,

however, serious strains have been placed on the mechanism, which it isthe object of my invention-to avoid.

According to my invention, the endless tracks are made laterallyflexible, prefer ably by means of a universal jomt between each pair oflinlrs composing the track. The driving pulleys andthe idlers for thebelts are suitably supported in the vehlcle frame, while the weight ofthe vehicle is earned by bogies or body supporting members which bear onthe lower runs of the belts and am yieldingly connected with the veinclebody. These body supporting members are so connected and so mounted asto allow the tracks to bend or flex laterally while still engaging thesupporting members and they are preferably so mounted that they can movenot only vertically but also laterally or horizontally to follow thelateral movements of the tracks when the latter are moved laterally andespecially when so moved during the steering o ration. The drivingpulleys are er with suitable brakes and these p *vertically or abouthorizontal axes.

able form of belt is shown in Figure 6 com eye are connected with brake.

each other by difierential gearing of the kind in which when the brakeis applied to one of the pulleys to reduce its speed, the

speed of the other pulley is corres ondingly or proportionallyincreased. ere are many kinds of such gearing'in the prior art which maybe employed and which are suitable for my pus. v By my invention atractor may be efficiently steered by merely applying the brake to oneof the driving pulleys and by reason of the laterally flexible tracksthe laterally movable body supporting members employed and thedifierential gearing used, the vehicle may be readily turned or steeredwithout undue strain on the mechanism.

In the accompanying drawings:

Figure 1 is a plan view ofso much of an endless track vehicle with myimprovements applied as is necessary to illustrate the invention hereinclaimed.

Figure 2 is a side elevation thereof.

Figure 3 is a plan view similar to Figure 1 but showing how the tracksare warped or bent laterally when the vehicle is being steered.

Figure 4 shows a transverse section of the vehicle.

Figure 5 is a sectional view showing details of a bogie or bodysupporting member.

Figure 6 is a plan view of a form of tree tor belt or track which may beemployed.

The frame or chassis is indicated at A and may be of any suitable kind.The endless belts or tracks B may be of any desired construction so longas they can be bent laterally or about vertical axes as well Asuitprising links or shoes 6 connected by universal or ball joints h.

The tracks traverse idle pulleys C mounted in beari in the chassis anddriving pulleys D applied to miles 0?, cl, the inner ends of which areconnected to ditlerential gearing within the housing E.

I have not shown-the details of the differential gearing employed asthere are many kinds that may be used. ll preferably,

however employ controlled differential gearing of the hind shown,described and claimed in the application tor shout out George JohnRackham, filed ugust '1 1922, N0. 57s on.

Each the l, a is provided with a suitable Preferably brake d ll andllllll are employed associatedwith brake bands f, g, operatedbytightenlng devices it actuated by Wires or cables H extending tosteerin mechanism L.

he pulleys C, D are raised above the ground level and the weight oftheyehrcle 15 carried by bogies or body supporting members M which bearon the lower runs of the belts or tracks. These body supporting membersmay take various forms, but they should be so mounted as to be adaptedto move laterally with the belts during the steering operaton.Preferably, each body supporting member comprises a pair of wheels Nmounted in a frame 0 through which extends a horizontally arranged rod Pthat'connects a body supporting member on one side of the vehicle with abody supporting member on the opposite side thereof. These frames 0 arefree to slide inde endently on the rods P to a limited extent. ach rod Pcarries posts p which extend into sockets a in downwardly projectingframe members R and springs S are interposed between the members R andthe clamps 7* which attach the posts to the rods.

The rollers or wheels N extend into grooves b in the track shoes and theconstruction is such that when the tracks are moved laterally the wheelsN with their frames 0 will also move laterally. It will the oppositeside of the vehicle.

therefore be seen that the body supporting devices or bogies are movedlaterally by the belts and with the belts whenever the belts are givenlateral movement for steering purposes or for any other reason.

, By means of the or anization shown the vehicle may be steere by merelyapplying the brake to one of the driving pulleys, causing it to slowdown and at the same time through the controlled diflerential gearingemployed, to speed up the driving pulley on The degree of increase maybe adjusted to any deslred extent by employing properly formed gearingmembers. i

By reference to Figure 3 it will be seen that if the brake is applied tothe brake drum F and loosened on the brake drum G the speed of thedriving pulley on the axle D will be reduced and the speed of the pulleyon the axle d will be increased, thus causin the tractor belt connectedwith the axle d to increase its speed, thus causing the vehicle to turnin the manner indicated by full lines, the normal or straight aheadposition of the parts being indicated by dotted lines. Full lines inFigure 3 show the relative positions of the parts in actual servicewhile steering.

' I clalm as my invention:

1. An endless track vehicle comprising a frame, endless flexible trackscarried thereby, a frame supporting member bearing on the lower run ofeach track and each mounted to move laterally in unison with acorresponding lateral movement of the portion of the track which itengages, driving pulleys and idlers for the tracks, differential earingconnecting the driving pulleys an independently operable brakestherefor, the application of either brake reducing the speed of theassociated pulley and correspondingly increasing the speed of the otherpulleyv to bend laterally only the lower reach of said track between thepulleyand idler and give lateral movement to the body supportingmembers.

2. An endless track vehicle comprising a frame, driving pulle s andidlers mounted thereon, endless traclts associated with the pulleys,differential gearing connecting the driving pulleys, a brake for eachdrivin pulley, independent means for applying and withdrawing each ofthe brakes, and body supporting members which bear on the lower runs ofthe tracks and transmit the weight of the vehicle thereto, which aremounted to move laterally or transversely of the vehicle with thelaterally movable'tracks, whereby steering is performed solely byapplication of brake to one pulley, therebyredu'cing its speed andincreasing the speed of the other pulley to bend the tracks laterallyand give lateral movement to the body support- 1ng members.

3. An endless track vehicle comprising a frame, driving pulleys andidlers mounted thereon, endless tracks or tractor belts associated withthe pulleys and comprising a series of shoes connected by jointspermitting the tracks to bend vertically and laterally, difl'erentialgearing connecting the driving pulleys, a brake for each driving pulley,independent means for applying and withdrawing each of the brakes andbogies which bear on the lower runs of the belts and transmit the weightof the vehicle thereto, which are mounted to move laterally ortransversely of the vehicle with the laterally mov-' ing belts, thesteering being performed solely by application of the brake to one ofthe driving pulleys to bend laterally only the lower reach of the trackand lay it down in a curve.

4:. An endless track vehicle comprising a vehicle body, laterallyflexible tracks associated therewith, differential gearing for dryingthe tracks, means for controlling the gearing to drive one track fasterthan the other, said means alone operating to bend the tracks .and steerthe vehicle, and body supporting rollers engaging the tracks and mountedfor lateral movement on the vehicle body, which allow the tracks to bendlaterally while still engaging the rollers.

5. An endless track vehiclepomprising a vehicle body, driving pulleysand idle pulleys associated therewith, dfferential gearing for actuatingthe driving ulleys, means for controlling the gearing to drive the trackthe vehicle body which allow the tracks to on one side of the vehiclefaster or slower bend laterally while still engaging the rollthan theother, said means alone operating ers.

to bend the tracks and steer the vehicle, In testimony whereof, I havehereunto 10 5 and body supporting rollers engaging the subscribed myname.

tracks and mounted for lateral movement on LEWIS K. DAVIS.

